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New research shows semen may trigger ovulation

August 22, 2012 2:20pm

Couples using the rhythm and withdrawal methods to prevent an unplanned pregnancy may want to think twice: a new study confirmed the fluid in semen may trigger ovulation and pregnancy-supporting hormonal responses in females.

Researchers led by veterinarian and reproductive biologist Gregg Adams of the University of Saskatchewan in Saskatoon, Canada claimed to have found the ovulation-inducing factor (OIF) in semen that could trigger ovulation, Huffington Post reported.

The article quoted Adams as saying the findings could also lead to OIF treatment for couples having a difficult time getting pregnant.

The article said the group’s findings, published in the Proceedings of the National Academy of Sciences, seemed to support the findings of a group of Chinese researchers as far back as 1985, that there might be an OIF in semen.

But Adams said the Chinese researchers’ hypothesis at the time was so counter to common wisdom that people, including himself, “just ignored it.”

In 2005, the team injected the seminal fluid of male llamas, which are closely related to camels, into the hind legs of female llamas to see if the llamas could ovulate without male genital stimulation.

Adams said they were surprised to learn merely injecting seminal fluid into the female llamas’ bloodstream had “a very potent ovulatory effect.”

7-year follow-up

During the next seven years, the researchers took samples of llama and bull semen to see if OIF could be found in the semen of both induced ovulating species and spontaneously ovulating species.

They spun the samples several times in centrifuges to separate the seminal fluid from the sperm, which Adams said makes up only about five percent of semen.

The team then used heat, protein-digesting enzymes, and size filters to try to winnow out the effective molecule.

Adams said the altered seminal fluid was injected into the female llamas’ hindquarters to see if the molecule had survived and effectively induced ovulation, or was destroyed.

To his surprise, the mystery substance turned out to be neural growth factor (NGF), a protein crucial to the development and survival of sensory neurons. “I didn’t know whether to be happy or sad about that,” he said.

Connecting the dots

Adams said NGF was discovered in bull semen in the early 1980s, but “it was one of those dangling facts that no one knew what to do with.”

He and his team then found the same molecule in abundance in the semen of other species they studied, including humans.

They also established the molecule facilitates reproduction across different species, and that while NGF does not appear to induce ovulation in the other spontaneous ovulator they studied, the cow, it has other fertility-boosting effects.

Adams said the first evidence that NGF, or OIF, from semen travels throughout the female body acting as a hormone, “is really new for us.”

The next step, he said, is to study how NGF affects human fertility.

“We’re really interested to know the relationship between OIF and infertility. Are males with high concentrations of OIF in their semen more fertile?” he said.

'Very exciting'

Sergio Ojeda, a neuroscientist at Oregon Health & Science University in Portland, said this research is “very exciting.”

Ojeda studies how neurotrophins, the class of proteins that includes NGF, act within the female reproductive system.

He said the new study indicates NGF in male sperm actually travels through the female bloodstream to the brain, causing her to release the hormones needed for pregnancy. — BM, GMA News